Hydrogen generation electrode and artificial photosynthesis module

Abstract

A hydrogen generation electrode is used for an artificial photosynthesis module that decomposes an electrolytic aqueous solution into hydrogen and oxygen with light. The hydrogen generation electrode has a conductive layer, an inorganic semiconductor layer that is provided on the conductive layer and has a pn junction, and a functional layer that covers an inorganic semiconductor layer. The steam permeability of the functional layer is 5 g/(m2·day) or less.

What is claimed is: 
     
       1. A hydrogen generation electrode for an artificial photosynthesis module that decomposes an electrolytic aqueous solution into hydrogen and oxygen with light, the hydrogen generation electrode comprising:
 a conductive layer; 
 an inorganic semiconductor layer that is provided on the conductive layer and has a pn junction; and 
 a functional layer that covers the inorganic semiconductor layer, 
 wherein the functional layer is made of amorphous ITO, 
 a steam permeability of the functional layer is 5 g/(m 2 ·day) or less, and 
 the functional layer is in contact with the electrolytic aqueous solution. 
 
     
     
       2. A hydrogen generation electrode for an artificial photosynthesis module that decomposes an electrolytic aqueous solution into hydrogen and oxygen with light, the hydrogen generation electrode comprising:
 a conductive layer; 
 an inorganic semiconductor layer that is provided on the conductive layer and has a pn junction; and 
 a functional layer that covers the inorganic semiconductor layer, 
 wherein the functional layer includes a plurality of layers, and has an amorphous ITO layer and at least one layer of an inorganic layer or an organic layer, 
 the amorphous ITO layer is disposed opposite to the inorganic semiconductor layer, 
 a steam permeability of the functional layer is 5 g/(m 2 ·day) or less, and 
 the amorphous ITO layer of the functional layer is in contact with the electrolytic aqueous solution. 
 
     
     
       3. The hydrogen generation electrode according to  claim 2 ,
 wherein the functional layer is configured such that the organic layer, the inorganic layer and the amorphous ITO layer are disposed in this order over the conductive layer. 
 
     
     
       4. The hydrogen generation electrode according to  claim 1 ,
 wherein PV≤t is satisfied when a thickness of the functional layer is t and a peak-valley value in a surface of the inorganic semiconductor layer is PV. 
 
     
     
       5. The hydrogen generation electrode according to  claim 2 ,
 wherein PV≤t is satisfied when a thickness of the functional layer is t and a peak-valley value in a surface of the inorganic semiconductor layer is PV. 
 
     
     
       6. The hydrogen generation electrode according to  claim 3 ,
 wherein PV≤t is satisfied when a thickness of the functional layer is t and a peak-valley value in a surface of the inorganic semiconductor layer is PV. 
 
     
     
       7. The hydrogen generation electrode according to  claim 1 ,
 wherein the inorganic semiconductor layer includes any one of a CIGS compound semiconductor, a CZTS compound semiconductor and a CGSe compound semiconductor. 
 
     
     
       8. The hydrogen generation electrode according to  claim 2 ,
 wherein the inorganic semiconductor layer includes any one of a CIGS compound semiconductor, a CZTS compound semiconductor and a CGSe compound semiconductor. 
 
     
     
       9. The hydrogen generation electrode according to  claim 3 ,
 wherein the inorganic semiconductor layer includes any one of a CIGS compound semiconductor, a CZTS compound semiconductor and a CGSe compound semiconductor. 
 
     
     
       10. The hydrogen generation electrode according to  claim 4 ,
 wherein the inorganic semiconductor layer includes any one of a CIGS compound semiconductor, a CZTS compound semiconductor and a CGSe compound semiconductor. 
 
     
     
       11. The hydrogen generation electrode according to  claim 5 ,
 wherein the inorganic semiconductor layer includes any one of a CIGS compound semiconductor, a CZTS compound semiconductor and a CGSe compound semiconductor. 
 
     
     
       12. The hydrogen generation electrode according to  claim 1 ,
 wherein the functional layer has platinum carried as a co-catalyst on a surface thereof. 
 
     
     
       13. The hydrogen generation electrode according to  claim 2 ,
 wherein the functional layer has platinum carried as a co-catalyst on a surface thereof. 
 
     
     
       14. The hydrogen generation electrode according to  claim 3 ,
 wherein the functional layer has platinum carried as a co-catalyst on a surface thereof. 
 
     
     
       15. The hydrogen generation electrode according to  claim 4 ,
 wherein the functional layer has platinum carried as a co-catalyst on a surface thereof. 
 
     
     
       16. The hydrogen generation electrode according to  claim 5 ,
 wherein the functional layer has platinum carried as a co-catalyst on a surface thereof. 
 
     
     
       17. An artificial photosynthesis module comprising:
 the hydrogen generation electrode according to  claim 1 ; and 
 an oxygen generation electrode. 
 
     
     
       18. An artificial photosynthesis module comprising:
 the hydrogen generation electrode according to  claim 2 ; and 
 an oxygen generation electrode. 
 
     
     
       19. An artificial photosynthesis module comprising:
 the hydrogen generation electrode according to  claim 3 ; and 
 an oxygen generation electrode. 
 
     
     
       20. An artificial photosynthesis module comprising:
 the hydrogen generation electrode according to  claim 4 ; and 
 an oxygen generation electrode.